Quick cycle biopsy system

ABSTRACT

A method for extracting a tissue sample includes altering the pressure inside the lumen of a cannula to facilitate extraction of a tissue sample from the cannula. One aspect of the invention includes a biopsy apparatus comprising a valve for controlling the pressure inside the lumen of the cannula. In one variation, the pressure/vacuum generating device is connected to a cannula with a closed distal end and an orifice located on a circumferential surface of said cannula. A cutting sheath is slidably disposed over said cannula. The valve may be provided between the pressure/vacuum generating device and the cannula to control the pressure within the lumen of the cannula.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO A COMPACT DISK APPENDIX

Not applicable.

BACKGROUND OF THE INVENTION

Various biopsy devices for taking tissues samples have been previously disclosed. Typically, the device comprises a hand piece, in which a portion of a hollow biopsy cannula/needle protruding from the hand piece is introduced with its sampling chamber into the tissue being investigated. A sample of the tissue is sucked into the sampling chamber by vacuum, separated by a sample separating mechanism, and then removed.

Examples of biopsy devices are disclosed in British Patent Publication No. GB 2018601A, European Patent Publication No. EP 0890 339 A1, U.S. Pat. No. 5,526,822, German Patent No. DE 40 41 614 C1, International Publication No. WO 96/28097, German Patent Publication No. DE 100 34 297 A1, International Publication No. WO 98/25522, and US Patent Publication No. 2001/0011156 A1, each of which is incorporated herein by reference in its entirety.

Integrated biopsy systems having built-in actuators for displacing a biopsy cannula and a corresponding cutting sheath and a pressure/vacuum generating device for suctioning and expelling tissue samples form the lumen of the cannula are described in U.S. patent application Ser. No. 10/500,518, entitled “BIOPSY DEVICE AND INSERTABLE BIOPSY NEEDLE MODULE” filed Jun. 29, 2004, and U.S. patent application Ser. No. 10/500,522, entitled “BIOPSY DEVICE FOR REMOVING TISSUE SPECIMENS USING A VACUUM” filed Jun. 29, 2004, each of which is incorporated herein by reference in its entirety.

Although various biopsy devices have been previously disclosed, it may be desirable to improve the reliability and efficiency of the present biopsy devices such that extraction and/or removal of the tissue sample from the tissues sample chamber within the biopsy cannula may be facilitated.

BRIEF SUMMARY OF THE INVENTION

One aspect of the invention comprises a method for facilitating the ejection/removal of a tissue sample from the tissue chamber within the biopsy cannula. The cannula may be inserted into a body of tissue within a patient to extract a sample of the tissue of interest. Once the sample tissue is pulled within the tissue chamber in the cannula through suction, the chamber is closed, severing the sample tissue from the patient's body. The cannula may then be removed from the patient's body. The tissue chamber is maintained in a closed position while the lumen of the cannula is pressurized. Once the pressure within the lumen of the cannula has reached a desired level, the tissue chamber is opened. The pressure behind the sample tissue will force the sample tissue to eject or move out of the tissue chamber. The operator may open only a distal portion of the chamber (e.g., exposing only the distal one-third or one-half of the chamber opening) to prevent the fluids from leaking through the side of the sample tissue, and force the sample tissue to exit from the partial opening. Alternatively, if the pressure is high enough, the operator may open the chamber completely.

Another aspect of the invention comprises a biopsy apparatus with an integrated valve for facilitating high and/or low pressure build-up within a pressure chamber for providing suction and/or ejection pressure to the lumen of the biopsy cannula. In one variation, the biopsy apparatus comprises a built-in pressure generator that is coupled to the proximal end of a biopsy cannula. The pressure generator may be capable of generating both a positive and a negative (e.g., vacuum) pressure within the lumen of the cannula. A valve is placed between the biopsy cannula and the pressure generator to control the fluid flow from the chamber of the pressure generator to the lumen of the biopsy cannula. An electronic system control board coupled to an actuator may be utilized to displace the biopsy cannula and its corresponding cutting sheath. The electronic system control board may also be adapted to control the pressure generator and the valve. In one application, the valve is placed in the open position when the pressure generator applies suction to the lumen of the cannula to extract a sample of the interested tissue into the chamber of the cannula. After the chamber is closed and the cannula is removed from the patient's body, the valve is closed and a positive pressure is built-up within the chamber of the pressure generating device. Once the tissue chamber has been opened, the valve may subsequently be opened to release the built-up pressure into the lumen of the cannula. The fluid inside the pressure chamber enters the lumen of the cannula and ejects the tissue sample out of the cannula. One of ordinary skill in the art having the benefit of the disclosure herein would appreciate that the valve may be utilized to build-up either positive or negative pressure inside the chamber to various pressure levels as desired by the operator. The valve may then be released to cause a sudden increase or decrease in pressure within the lumen of the cannula.

These and other embodiments, features and advantages of the present invention will become more apparent to those skilled in the art when taken with reference to the following more detailed description of the invention in conjunction with the accompanying drawings that are first briefly described.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a cross-sectional view of a variation of a biopsy apparatus where the biopsy cannula is connected to a pressure generating device.

FIG. 1B is a perspective view of the distal portion of the biopsy cannula of FIG. 1A. The cutting sheath is shown in a retracted position exposing the tissue chamber in the lumen of the biopsy cannula.

FIG. 1C illustrates the distal portion of the biopsy apparatus of FIG. 1A with the cutting sheath advanced over the tissue chamber.

FIG. 2 illustrates a biopsy apparatus integrated within a housing with actuators for moving the biopsy cannula and its corresponding cutting sheath.

FIG. 3 illustrates another variation of a biopsy apparatus with an integrated valve for controlling fluid flow from the pressure generator to the lumen of the biopsy cannula.

FIG. 4 is a diagram illustrating yet another variation of the biopsy apparatus where a bifurcating valve system is utilized to control pressure distribution within the apparatus.

FIG. 5A shows another variation of a biopsy apparatus with its housing cover opened (perspective view).

FIG. 5B shows a partially disassembled biopsy apparatus of FIG. 5A. The primary components are fixed to a housing (shown without the housing cover) and the replaceable biopsy unit is shown separated from the main housing (perspective view).

FIG. 5C shows a lengthwise section of the biopsy apparatus of FIG. 5A.

FIG. 5D shows the base block of the biopsy apparatus of FIG. 5A (perspective view).

FIG. 5E shows the main housing/frame of the biopsy apparatus of FIG. 5A with its corresponding actuator/driver and spring-load displacement system. The components are shown without the housing cover, and with the spring-load displacement system in an uncocked condition.

FIG. 5F is a cross-sectional view of the biopsy cannula and its corresponding cutting sleeve of the biopsy apparatus of FIG. 5A. The cannula is shown with its tissue sample chamber partially opened.

FIG. 5G illustrates the biopsy cannula carrier with press-fitted biopsy cannula/cutting sheath and plastic holder(perspective view).

FIG. 5H shows the pressure generating device integrated with the biopsy cannula carrier and installed on the main housing (perspective view).

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description should be read with reference to the drawings, in which identical reference numbers refer to like elements throughout the different figures. The drawings, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of the invention. The detailed description illustrates by way of example, not by way of limitation, the principles of the invention. This description will clearly enable one skilled in the art to make and use the invention, and describes several embodiments, adaptations, variations, alternatives and uses of the invention, including what is presently believed to be the best mode of carrying out the invention.

Before describing the present invention, it is to be understood that unless otherwise indicated, this invention need not be limited to applications in humans. As one of ordinary skill in the art would appreciate, variations of the invention may be applied to various other animals and plants as well. Moreover, it should be understood that embodiments of the present invention may be applied in combination with various imaging devices (e.g., ultrasound, X-ray, etc.) for guiding the surgeon on the placement of the biopsy needle/cannula within a patient's body.

Taking biopsy of a tumor tissue is used herein as an example application of the biopsy apparatus and method disclosed herein. In light of the disclosure herein, one of ordinary skill in the art would appreciate that variations of the apparatus and/or method may be applicable for extracting samples from various types of tissues within the human body.

It must also be noted that, as used in this specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, the term “an actuator” is intended to mean a single actuator or a combination of actuators, “a fluid” is intended to mean one or more fluids, or a mixture thereof. Furthermore, the words “proximal” and “distal” refer to directions closer to and away from, respectively, a physician operating the biopsy cannula, with the tip end (i.e., distal end) placed inside the patient's body. Thus, for example, the cannula end placed in the tissue of the patient would be the distal end of the cannula, while the cannula end outside the patient's body would be the proximal end of the cannula.

One aspect of the invention comprises a method of building up a pressure inside the biopsy apparatus to eject a tissue sample captured in the chamber of the device. In one variation, the method comprises providing a biopsy cannula having a closed distal end and an orifice located on a circumferential surface of said cannula. An example of such a biopsy apparatus 201 is shown in FIG. 1A. The orifice 202 on the circumferential surface of the cannula forms the opening for access of a tissue chamber 71 at the distal end of the lumen 203 of the cannula 2, as shown in FIG. 1A. A cutting sheath 3 is slidably disposed on the cannula 2. The cannula 2 with orifice 202 covered by the sheath 3, as shown in FIG. 1C, can be inserted into a body of tissue inside a patient. A needle or cannula guide may be first inserted into the tissue to guide the insertion of the biopsy cannula. A mechanical displacement mechanism, such as spring loaded lever or driver, may be used to eject and/or force the biopsy cannula 2 and its corresponding cutting sheath 3 into the desired body of tissue. A negative pressure (pressure lower than either tissue surrounding the cannula and/or the atmospheric pressure) is generated inside the lumen of the cannula. The negative pressure may be generated prior, during and/or after the insertion of the cannula/sheath unit into the tissue of interest.

Once the distal end 204 of the cannula 2 is in place, the cutting sheath 3 may be retracted toward the proximal end of the cannula to expose the orifice 202. A suction draws a portion of the desired tissue into the tissue chamber 71 within the lumen of the cannula 2. In one particular design, a stopper 79 is positioned within the lumen 203 of the cannula 2, proximal to the orifice on the cannula. The distal end of the stopper along with the wall of the cannula lumen forms a tissue chamber 71 at the distal portion of the cannula. The stopper 79 partially blocks the lumen to allow fluid flow in the unobstructed portion 205 of the lumen, but to prevent the captured tissue sample from migrating in the proximal direction. Once the tissue is captured within the tissue chamber 71, the cutting sheath 3 may be advanced in a distal direction to cover the orifice 202 on the cannula 2, which acts to sever the sample tissue from the body of tumor tissue in the patient. The distal tip 72 of the cutting sheath 3 may be advanced past the distal edge 206 of the tissue chamber to achieve a clean separation between the sample tissue and the primary body of tissue of interest. The cannula 2 and its corresponding cutting sheath 3 may then be removed from the patient's body.

While the cutting sheath is closed, a positive pressure (a pressure higher than atmospheric pressure) is generated within the lumen 203 of the cannula 2. As shown in FIG. 1A, a pressure generator 207, such as a cylinder with a single piston, may be utilized to generate the negative and positive pressure within the lumen 203 of the cannula 2. In the particular example shown in FIG. 1A, to release the negative pressure inside the lumen of the cannula, the piston 210 may be retracted past the release port 208 such that the pressure within the lumen 203 of the cannula 2 and the pressure chamber 209 of the pressure generator can normalize. The piston 210 may then be advanced in the distal direction to compress air in the lumen 203 of the cannula 2. Once the positive pressure within the lumen 203 reaches a predefined level (e.g., the piston has been advanced a predefined distance; a pressure sensor 299 is utilized to verify the pressure inside the lumen, etc.), the cutting sheath 3 is retracted in a proximal direction to expose the tissue sample within the tissue chamber 71. One may open the chamber 71 in increments. For example, one may initially open the chamber 71 only the distal one-third or one-half thereof. Alternatively, one may fully open the chamber at once. The pressure that has built-up behind the tissue sample will force the tissues sample to eject out of the tissue chamber 71.

Referring to FIG. 2, a variation of the biopsy apparatus is shown with a housing 211 and integrated actuators/drivers 212 for displacing the cannula 2, the corresponding cutting sheath 3, and the piston 210. A spring-loading mechanism or other similar ejector may be implemented for the insertion of the biopsy cannula 2 and its corresponding cutting sheath 3. An electronic controller board with an on-board processor may be utilized to control and synchronize the action of all the associated actuator and displacement mechanisms in the integrated biopsy apparatus. An optional needle/cannula guide 213 may be utilized to guide the insertion of the cannula/sheath unit. One of ordinary skill in the art would appreciate that other pressure/vacuum generating devices may also be implemented in place of the cylinder/piston unit.

By changing the program control parameters in an integrated biopsy device, such as the one shown in FIG. 2, air pressure can be accumulated and released all at once instead of in a gradual manner. For example, before the chamber is opened, the controller may depress the piston within the cylinder by a predetermined distance to generate a positive pressure and hold the piston in place to maintain the pressure. Thereafter, the tissue chamber is exposed by sliding open the chamber cover (i.e., cutting sheath). As soon as the tissue sample fits through the opening space, it will shoot out of the biopsy cannula. In the particular design shown in FIG. 2, because the lumen opening 214 for delivering the pressure is at the proximal end of the tissue chamber 71 close to the base 215 of the chamber, opening of the chamber cover at the distal end 216 first may prevent premature leakage of the fluid pressure and allow the fluid pressure to push the captured sample all the way through the chamber, and in the process clear the chamber of any particles.

In another aspect of the invention, as shown in FIG. 3, a valve 218 is implemented to allow positive or negative pressure to build-up with the pressure generation device 207 such that instant pressure increase or decrease can be realized with the release/opening of the valve 218. Alternatively, a large positive or negative pressure may be created within the pressure chamber 209 of the pressure generating device 207, and the valve 218 may be utilized to control the release of the positive/negative pressure into the lumen of the cannula 2. In addition, a seal (e.g., O-ring) 219 may be placed between the cannula and its corresponding cutting sheath to prevent the leakage of negative pressure that has been generated in the surrounding tissue when the tissue chamber 71 is opened inside the patient's body. An additional seal (e.g, O-ring) 220 may also be provided between the cannula guide 213 and the cutting sheath 3.

In one example application, with the assistance of an ultrasound imaging device, a cannula guide 213 is inserted into a body of tumor tissue within the patient's body. The cannula 2 with its tissue chamber 71 covered and placed in a spring-loaded cocked position is inserted into the cannula guide and advanced toward the tissue. The spring-loaded cannula is then released, shooting into the tumor tissue. With the cannula 2 in place, the piston 210 in the pressure generating device 207 is retracted to regenerate a negative pressure within the lumen of the cannula 2. The cutting sheath is subsequently retracted to expose the orifice to the tissue chamber. A sample of the tissue is suctioned into the tissue chamber 71. A delay may be built into the control protocol to ensure that the tissue chamber 71 is loaded before the cutting sheath 3 is slid back into the closed position. In an alternative approach, the valve may be closed and a negative pressure generated within the chamber 209 of the pressure generating device 207 prior to or after the cutting sheath is retracted and the chamber is opened. With the cannula 2 inserted inside the tumor tissue and the orifice to the tissue chamber in an open position, the valve 218 may be opened to provide the suction to capture a sample of the tumor tissue within the tissue chamber.

Once the sample of tissue is suctioned into the tissue chamber 71, the cutting sheath 3 is advanced forward of the orifice of the tissue chamber 71, severing the sample tissue in the chamber from the body of tumor tissue. With the sample tissue secured in the tissue sample chamber 71, both the cannula 2 and the cutting sheath 3 are withdrawn from the patient's body. Either prior to, during, or after the cutting sheath 3 is retracted to expose the captured tissue sample, the valve 218 may be closed and positive pressure generated in the pressure chamber 209 inside the pressure generating device 209 by compressing the piston 210. With the cutting sheath 3 retracted and the orifice of the tissue sample chamber 71 at least partially exposed, the valve 218 may then be released to direct a positive pressure into the lumen 203 of the cannula 2 to force the sample tissue out the cannula 2. The steps described above may be executed through manual control, or may be programmed into an electronic controller that is linked with the actuators/drives to synchronize the various components and carryout the desired procedure.

FIG. 4 illustrates another valve implementation to control pressure build-up and release within a pressure chamber. In this configuration, a bifurcate 221 with two valves 222, 223 are provided between the pressure generating device 209 and the biopsy cannula 2. A first valve 222, which is inline with the cannula 2 and the pressure generating device 207, controls the release of pressure into the lumen of the cannula 2. A second valve 223 on the bifurcating branch is provided for releasing pressure from the system or allowing inflow of air into the pressure chamber 209. The valves 222, 223 may be coupled to actuators that are linked to an electronic system controller.

A particular variation of a biopsy apparatus is illustrated in FIG. 5A. Integrated in a housing interior of a hand piece 1 are all devices and components required to perform a vacuum biopsy (FIG. 5A), so that no cables or lines are required going from the housing of the hand piece to other external supply devices. Thus, the hand piece 1 constitutes a complete vacuum biopsy apparatus, which is freely moveable in all directions. The apparatus is shown with an optional valve 150 for controlling the fluid flow from the vacuum/pressure generating unit 5, through the connection element 4, to the proximal end of the biopsy cannula. The valve may further comprise a control knob 151 to allow the operator to manually open the valve and release the pressure inside the pressure chamber of the vacuum/pressure generating unit 5. Alternatively, the valve 150 may be coupled to an actuator, which is linked to an electronic system control board. The electronic system control board may open and close the valve through controlling the actuator. The actuator may be positioned below the base board with levers or other mechanical interface 152 (FIG. 5B), extending above the base board, for coupling with the valve mechanisms. One of ordinary skill in the art, having the benefit of this disclosure, would appreciate that other fluid flow control mechanisms may be implemented in place of the valve to control positive and/or negative pressure build-up inside the pressure chamber of the vacuum/pressure generating unit 5.

In applications where pressure build-up is regulated by keeping the tissue chamber closed during pressurizing and depressurizing of the pressure generating device, the apparatus 1 may be fabricated without the control valve 150, and the connection element 4 may be directly connected to the pressure generating device 5.

From the distal part of the distal end cover 6 protrudes the distal part of the hollow biopsy cannula 2, with the cutting sheath 3 surrounding it coaxially, which is required to remove the tissue sample. Usually, a coaxial cannula guide is placed into the tissue first, into which the biopsy cannula 2 with cutting sheath 3 is inserted. Outside the proximal end cover 7 of the housing there is arranged a connection element 4 (e.g., a transparent flexible hose) which connects the valve and the vacuum pressure generating device 5, arranged in parallel with the biopsy cannula, to the interior cavity of the biopsy cannula 2. The hollow connection element 4 is situated in immediate proximity to the end cover 7 of the housing. The biopsy cannula with cutting sheath and additional elements, arranged in a biopsy cannula carrier 37, forms together with the connection element 4 and the vacuum pressure generating device 5 an element 20, easily inserted or taken out at the top, which is replaced as necessary (FIG. 5B). The housing cover 10 is opened for this purpose. As FIG. 5B in particular shows, the biopsy device can be divided into parts which are firmly connected to the housing (disinfected parts) and a removable element 20 (sterile part). While the parts firmly connected to the housing are merely disinfected, the removable element 20 may come in a sterile package and can be replaced as necessary, especially for each new patient.

The removable insert element 20, comprising a vacuum pressure generating device 5, elastic connection element, biopsy cannula carrier 37 with cannula and cutting sheath and additional elements connected to it, also contains a guide roller 81 mounted on the cannula. This unit, including an insert aid, comes in a sterile package. The plunger in the syringe body of the vacuum/pressure generating unit 5 comes slightly (about 1-2 mm) displaced from the syringe bottom and the sample removal chamber 71 of the biopsy cannula 2 may be open to improve sterilization within the chamber. After opening the housing cover 10, the carrier element 37, including biopsy cannula 2, cutting mechanism 3, and other parts connected with it, such as the vacuum pressure generating device 5 hooked up to the connection element 4, is inserted into the connection element provided for this (FIG. 5B). FIG. 5G shows the biopsy cannula carrier from the under side with the components, for coupling the biopsy cannula 2 and the cutting sheath 3 to the gear motor 21, exposed.

During the insertion process, the operator should check to ensure that the gear 74 engages with the teeth of the toothed roller 23; that the cutting sheath is inserted from above into the U-shaped holder 36, and at the same time that the brackets 40 of the tension slide are introduced into the recesses 77 of the carrier element; the guide roller 81 is inserted in the passage 13, so that the flanks 101 and 102 embrace the distal end cover 6. The cutting sheath 3 is mounted in the guide roller 81, able to move lengthwise and turn freely; the guide roller 81 itself, however, can no longer move relative to the cutting sheath 3 after being inserted in the distal end cover 6, as illustrated in FIG. 5B. The vacuum pressure generating device 5 is then inserted onto the base block 8, with its connection piece 63 inserted into the U-shaped, upward-open passage 16 on the base block 8. The connection piece 63 lies above the switch pin 19.

When the housing cover is closed, the connection piece 63 is forced downward and activates the miniature switch by the switch pin 19 built into the end cover of the housing. This activates the electrical control system, which is indicated by blinking of the reset diode on the control panel located at the left side 113 of the hand piece 1. The reset diode at first blinks yellow, which means that the positioning of the individual elements, i.e., the inserting process, is not yet finished; the DC gear motor 21 first open the sample chamber 71 all the way (at which point the motor feels resistance and calibrate that point), it then rotates the other direction a certain predetermined number of revolutions until the sample chamber 71 is closed with the cutting sheath 3. This occurs by twisting the threaded casing connected to the cutting sheath. The cutting sheath moves in the distal direction until the gear 74 comes to bear against the inside of the holder 36. In one variation, the controller is able to calibrate the displacement by counting the number of the rotation during the reset sequence, and then uses that information to start and stop the rotation rather than relying on the physical stops. After closing the sample removal chamber, the plastic disk 78 bears against the holder 36 (inside). During this process, or before or after it, the DC gear motor 58 brings the syringe plunger to bear against the syringe bottom. FIG. 5H shows the removable insert element 20 inserted on the main housing frame 153.

After the starting positions have been established for the vacuum pressure generating device and the biopsy cannula/cutting sheath, the cocking diode lights up yellow and the sample removal diode light up green and the reset diode goes out. The operator must now decide whether to initiate the cocking of the tension slide or to remove an additional sample, e.g., because he has already previously removed one tissue sample. If the operator presses the cocking button, the cocking of the tension slide is initiated; the cocking diode blinks yellow, the pierce diode blinks green, and the sample removal diode goes out. By pressing the cocking button, the electrical DC gear motor 21 receives current and the DC gear motor actuates the toothed roller 23. The gear 74 meshing with the toothed roller 23 turns the spindle shaft and at the same time the cutting sheath 3 connected to it. Since the spindle nut 75 is press-fitted in the biopsy cannula carrier 37 and the gear 74 is supported against the holder 36, which is firmly connected to the housing by the base block 8, the turning of the threaded spindle casing 73 has the effect of moving the biopsy cannula carrier in the proximal direction.

At the same time, the biopsy cannula 2 connected to the biopsy cannula carrier by the bearing element 49 is carried along, resulting in the tip of the biopsy cannula moving into the cutting sheath. The biopsy cannula carrier 37 is displaced in the proximal direction by the recess/bracket connection of the tension slide against the action of the spiral spring 31 until the lever of the locking element is forced into the recess of the tension slide by the spring. The tension slide is locked in this position. The gear motor receives the control command that the locking position has been reached, e.g., via a photocell installed in the sliding surface of the cover plate or based on the number of rotations by the motor, which interacts with the retracted biopsy cannula carrier; the direction of turning of the motor is reversed and the cutting sheath is displaced in the proximal direction by the amount that the cutting sheath had moved beyond the tip of the biopsy cannula by the movement of the tension slide and the biopsy cannula.

At the end of this step, the cutting sheath completely closes the sample removal chamber, as at the start of the cocking process. The locking diode lights up green; the blinking of the cocking diode goes out. Now, the biopsy cannula of the biopsy mechanism is inserted, for example, in a previously mounted coaxial cannula. The proximal end of the mounted coaxial cannula receives a seal, designed so that it seals off the space between cutting sheath and cannula, on one hand, and allows an easy insertion of the biopsy cannula with cutting sheath, on the other. The seal ring prevents air from the outside getting sucked in through the space between cannula and cutting sheath. The seal ring likewise prevents fluid (cytological material) from escaping after the biopsy cannula is introduced or inserted. Thus, the possibility of the disinfected hand piece 1 getting dirty is nearly precluded; on the other hand, the flank 101 of the sterile guide roller 81 prevents the sterile cannula from getting dirty by reason of the hand piece 1. The tip of the biopsy cannula is brought up in the cannula to the tumor and, after being correctly positioned, thrust into the tumor.

The shot is triggered by pressing the activation button on the control interface panel. This has the result of swiveling the double-arm lever about the axis to release the tension slide. The tension slide is hurled in the distal direction by spring action. The sample removal diode lights up green and the cocking diode goes out. By operating the program button, the sample removal sequence is enabled; the sample removal diode blinks green. At first, the DC gear motor 58 will activate the vacuum pressure generating device. The plunger of the vacuum pressure generating device is moved in the direction of the base block, i.e., away from the bottom of the syringe, until it reaches a position just before clearing the ventilation borehole 67. The vacuum is generated in the system. After reaching its end position, the system activates the motor 21, the cutting sheath which closes the sample removal chamber is opened via the gear/spindle drive. During the opening process, the partial vacuum prevailing in the system sucks in the tissue and any cytological fluid (cytological material) into the sample removal chamber. Cytological fluid may also flow due to the vacuum in the biopsy cannula cavity and the vacuum pressure generating device.

It has proven to be advantageous to direct the partial vacuum by the stopper 79 primarily at the lower region, the lower side, of the sample removal chamber, and the stopper 79 will prevent or impede tissue from getting into the biopsy hollow cannula. When the sample removal chamber is fully open—the tissue sample is accommodated in the sample removal chamber—the gear motor 21 is reversed and the sample removal chamber 71 is closed. By turning the cutting sheath, the tissue is separated by the cutting edge 72 of the sheath 3 during the closing process. In order to reliably cut through the tissue filaments, it is advantageous to move the cutting sheath 3 beyond the distal end of the sample removal chamber (around 2 mm). In order to accomplish this, it is only necessary to program accordingly the microprocessor where the control data is kept. Because of the special configuration of the sample removal chamber and thanks to the vacuum applied, the tissue sample is held in the chamber without torsion, so that the tissue sample is not twisted or turned by the rotating and lengthwise moveable cutting sheath 3 which surrounds the biopsy cannula on the outside, as described.

After the sample removal chamber is closed, the DC gear motor is activated for the vacuum generating unit 5. The plunger is first retracted far enough to clear the ventilation opening 67 (FIG. 5F). After the vacuum is dissipated in the system, the plunger travels toward the vacuum bottom until the ventilation borehole 67 is again closed, in order to prevent the outflow of bodily fluid (cytological fluid). The blinking of the sample removal diode goes out. The ejection diode lights up yellow. The biopsy cannula with closed sample chamber is extracted from the cannula guide.

After the removal of the biopsy unit and providing a vessel to receive the tissue sample and fluid, the program button is again operated and the ejection diode starts to blink. First, the DC gear motor 58 of the vacuum pressure generating device is activated while the sample removal chamber remains closed. The turning direction of the DC gear motor 58 remains and the threaded spindle with plunger moves in the direction of the syringe bottom, so that now an excess pressure is created in the system. After this, the gear motor 21 of the cutting sheath is operated to open the sample removal chamber roughly halfway. As soon as the sample fits through the opening it will shoot out of the biopsy chamber.

In a system with a built-in valve 150, an alternative approach may be used to eject the sample from the sample removal chamber. After the removal of the biopsy unit from the patient, the actuator coupled to the valve is activated to close the valve 150. With the valve 150 closed, the DC gear motor 58 of the vacuum pressure generating device is activated. The turning direction of the DC gear motor 58 remains and the threaded spindle 53 with plunger moves in the direction of the syringe bottom, so that now an excess pressure is created in chamber of the pressure generating device. After this, the gear motor 21 of the cutting sheath is operated to open the sample removal chamber roughly halfway. The actuator couple to the valve is activated to open the valve and release the pressure into the biopsy cannula, and force the sample out the biopsy chamber 71.

With the release of the excess pressure build-up in the vacuum/pressure generating unit 5, the sample is forced out due to the a pressure pulse and ejects into a waiting laboratory vessel even when the sample removal chamber is halfway open, and at the same time the chamber of the vacuum pressure generating device, the biopsy cannula and the sample removal chamber is cleared of tissue particles and fluid. The ejection of the sample when the sample removal chamber is around halfway open is so that the ejection of the tissue sample is assured and the tissue sample does not fall back into the chamber as a result of premature dissipation of the excess pressure. The narrowing of the cavity of the biopsy cannula by the stopper 79, which prevents or impedes tissue from getting into the cavity of the biopsy cannula, proves to be especially advantageous when removing the sample, since the narrower cross section boosts the ejection pressure. The best ejection results, therefore, may be achieved with the sample removal chamber halfway open; i.e., the cutting sheath clears half of the sample removal chamber. The excess pressure also forces tissue fluid out of the sample removal chamber and cleans it.

In the example illustrated in FIG. 5A, the vacuum pressure generating device is arranged in parallel with the biopsy cannula. However, the vacuum pressure generating device may also be arranged lying in the axis of the biopsy cannula or the hand piece; neither does it require its own connection element, if for example it is mounted directly on the end of the biopsy cannula.

The components of the exemplary device shown in FIG. 5A and FIG. 5B are now described in further detail. The gear motor 21 for the cocking mechanism and the cutting sheath is located at the distal lower-left portion of the housing interior, while the actuating mechanism 105 (FIG. 5H) for the vacuum pressure generating device 5 is positioned at distal lower-right portion of the housing interior. In the bottom proximal section is accommodated the energy supply for the actuating motors and the other electrical parts, such as for the control and/or monitoring elements; preferably, batteries or a storage battery are used for this, e.g., a 7.2 V lithium ion battery, 1 Ah. The proximal portion of the housing interior space above the battery compartment, is utilized mainly for the tension slide 28 with locking piece (FIG. 5C); this is connected to a block 26, which is part of the base block 8. The battery compartment is sealed on top by a separation plate.

In the upper-left part of the housing interior there is arranged a biopsy cannula carrier 37, which can be inserted into and taken out from the U-shaped insert holder 36 of the base block 8, which is open at the top, and the bracket 40 arranged on either side of the tension slide 28 and pointing upward; the biopsy cannula/cutting sheath unit with actuating parts is moveably mounted in this, extending for almost the entire length of the hand piece. This means that, in the uncocked state, the distal end surface of the biopsy cannula carrier 37 lies against the distal end cover 6 of the housing, and in the cocked state the proximal end surface lies against the proximal end cover 7. “Almost the entire length” means that the biopsy cannula carrier is at least shorter by the distance required in the interior of the housing for the cocking sequence. If the cocking distance of the tension slide is 20 mm, for example, the biopsy cannula carrier must be able to move by this amount. In this particular design, the cocking distance set at 20 mm. As one of ordinary skill in the art having the benefit of this disclosure would appreciate, the device may be adapted to allow the physician to adjust the device to capture the desired length of the sample.

The cocking device itself consists of a tension slide 28, placed on a bolt 30, the bolt screwing into the base block 8. The bolt 30 has a spiral spring 31 surrounding it. The locking device of the tension slide is secured to the block 26. In the upper-right proximal interior of the housing is accommodated the vacuum pressure generating device 5 with parts of the actuator; the actuating motor with reduction gearing for the vacuum pressure generating device is located in the distal lower-right area of the housing interior.

At the left side of the bottom piece of the housing there is a surface 113 provided for the control interface panel with the operating and monitoring elements (FIG: 5A). The control interface panel secured to the housing is designed as an independent component, which is glued, for example, onto the surface 113 of the bottom piece 9. This control interface panel is connected by lines to other electronic components arranged in the housing, and to the power supply. The board contains in particular switches for the operation and diodes for the monitoring. The activating button for mechanical triggering of the cocked tension slide protrudes through a recess 65 in the bottom piece of the housing and the board.

When configuring the operating and monitoring elements on the control interface panel consideration was given to the difference between the cocking sequence of the tension slide and the triggering of the tension slide, on one hand, and the performance of the biopsy, such as the cutting out of the sample, as well as the removal of the sample with the ejection of the sample, on the other hand. Accordingly, the activating button (trigger) for the tension slide has been placed at the right and the cocking button for cocking the tension slide is at left. The program button for performing the biopsy is in the middle. It is necessary to press the program button for three functions. The first function, start or reset, is indicated by the reset diode, while the sample removal diode arranged underneath indicates the opening and closing of the sample removal chamber when removing the sample. The lowermost eject diode indicates the ejection of the removed sample. The cocking diode indicates the cocking of the tension slide; the locking diode indicates the locking of the tension slide. The battery charge diode indicates the charge condition of the battery or storage battery. The diodes are switched so that the diode blinks while performing the particular sequence and after completion of the sequence the next diode lights up. When there are two possible choices, both diodes are lit. The operator is then free to make a choice. The mode of operation and possibility of control shall be examined more closely in detail when describing the sequence. Symbols (icons) at the margin symbolize the individual processes.

To improve the operating safety it may be advisable to outfit individual automated sequences with delay circuit. In particular, it has been found that the processes of “cocking of the tension slide” by pressing the cocking button and “ejection of sample” by pressing the program button are provided with delay circuits of around 1.2-1.5 seconds to improve the operating safety. Furthermore, the operating safety is improved when the light-emitting diodes indicating the individual processes have different colors for processes outside and processes inside the tissue.

A perspective representation of the base block 8 is shown in FIG. 5D. The base block 8 can be divided into two halves, looking down the lengthwise direction; the left side serves to secure the joint actuation for cutting sheath and tension slide, and also in its upper part to mount the biopsy cannula carrier; the right side serves to secure the actuation for the vacuum pressure generating device and to mount one side of the vacuum pressure generating device. Between the two actuating motors 21, 58, beneath the center rib 87, is arranged a central electronic system control board. The base block 8 has a U-shaped space 24, in which is installed a toothed roller 23, driven by the gear motor 21. For this, the take-off shaft of the gear motor is mounted or inserted in an opening in the wall 25 of the base block 8. The toothed roller 23 is mounted on the take-off shaft and secured to it, for example, by means of a set screw, so that it cannot turn or shift. At the other end, the toothed roller 23 is mounted in the wall 22 of the base block 8. The actuating motor used is a DC motor with a speed of around 11000 rpm. The DC motor is connected to a planet gear with high reduction ratio (e.g., 67:1), on whose take-off shaft the toothed roller 23 is mounted.

An additional block 26 is machined form the wall 22, pointing in the proximal direction, which accommodates both the swiveling double lever 33 for the locking process and also serves to fasten the bolt 30 for guiding the tension slide 28. The bolt 30 is screwed into the threaded borehole 29. During the cocking process, the tension slide 28 moves in the proximal direction on the bolt 30 and the separating plate arranged underneath. The spiral spring 31 arranged on the threaded bolt 30 is compressed during the cocking process. At one end, the spiral spring thrusts against an end piece 32 of the threaded bolt or directly against the end cover 7 of the housing; the other end of the spiral spring thrusts against the end of the guide borehole of the tension slide.

The tension slide 28, which adjoins the block 26, is arranged at equal height and is roughly equal in cross section. On its top side, the tension slide has two brackets 40. The upward pointing surface 41 of the tension slide, as well as the upward pointing surface 44 of the block 26, and the upward pointing surface of the extension 42 of the basic block 8, together form a planar bearing surface for the lower sliding surface 43 of the biopsy cannula carrier 37 mounted thereon. The biopsy cannula carrier is made of plastic. As the tension slide is moved from the starting uncocked condition (FIG. 5E) to the cocked condition, i.e., in the proximal direction, the biopsy cannula carrier 37 held by the brackets 40 slides across the surface 42 and 44. It is also conceivable that the sliding surfaces are configured not planar, as in the sample embodiment, but instead have specially configured sliding surfaces; the important thing is that the biopsy cannula carrier 37 can slide easily and straight on the sliding surface and the biopsy cannula can penetrate straight into the tissue, or tumor, after triggering the activation button. Therefore, the upper outer contour of the biopsy cannula carrier is also configured correspondingly to the inner contour of the housing cover and has only slight play relative to the housing cover in order to prevent the biopsy cannula from deviating upward.

FIG. 5B shows the biopsy cannula carrier 37, which can be inserted into the brackets 40 of the tension slide 28 with biopsy cannula 2 and cutting sheath 3, as well as other parts. The hollow, round circular biopsy cannula 2 has a needle tip, which adjoins the sample removal chamber 71 (FIG. 5F). The biopsy cannula 2, which is round in cross section, is surrounded by a coaxially arranged cutting sheath 3, round in cross section, having a cutting edge 72 at its distal end, facing the sample removal chamber, which serves to cut out the tissue sample after the biopsy cannula is introduced (with sample removal chamber closed) and after the sample removal chamber is opened and the sample is sucked into the sample removal chamber. The cutting edge preferably stands perpendicular to the lengthwise axis of biopsy cannula and cutting sheath. The cutting process occurs by rotation and simultaneous lengthwise displacement of the cutting sheath by means of the threaded spindle drive. It is also contemplated that the motion occurs not continuously, but stepwise or vibrating, i.e., the feed process moves back and forth with short intervals. For example, the gear motor 21 is reversed for 2 mm, then reversed again for 2 mm, in a cutting motion that is repeated again before the sample removal chamber 71 is advanced all the way forward and closed. The forward and reverse motion causes the sharpened edge of the cannula 72 to cut the tissue while it is drawn into the sample chamber by the vacuum.

At the other, proximal end of the cutting sheath, away from the cutting edge 72, there is fastened a threaded spindle casing 73 with a gear 74 arranged at the end face of the threaded spindle casing. The threaded spindle casing with gear is arranged on the cutting sheath and prevented from turning and shifting. The threaded spindle cooperates with a threaded spindle nut 75, which is firmly press-fitted in the biopsy cannula carrier 37. The gear 74 lies next to the nut 75, i.e., before the spindle casing begins. When the threaded spindle casing is turned by means of the gear 74, the cutting sheath is rotated and shifted in lengthwise direction along the biopsy cannula 2.

The gear 74 at the distal end of the threaded spindle engages with the toothed roller 23 after the biopsy cannula carrier is inserted in the brackets 40. So as to allow for inserting the biopsy cannula carrier 37 into the brackets of the tension slide when the slide is not cocked (FIG. 5B), the biopsy cannula carrier has two plane parallel recesses 77. When the sliding surface of the biopsy cannula carrier 37 is placed on the surfaces 41, 42 and 44, at the same time the cutting sheath is inserted in the holder 36 of the base block 8. To improve the turning of the spindle drive, especially when the holder 36 is used to support the cocking of the tension slide, a plastic disk 78 may be inserted at the distal side of the gear, being provided with a slight cone. When the biopsy cannula carrier is correctly inserted, it slides to the proximal end by the sliding surface 43 over the surfaces 42 and 41 when the tension slide is cocked. Since the specimen removal chamber is only closed after inserting the biopsy cannula carrier, the gear 74 bears against the holder 36. Now, if the toothed roller 23 is driven further in the same direction, the threaded spindle drive will screw the tension slide in the proximal direction along the biopsy cannula carrier, until it locks; the biopsy cannula will be pulled inward, while the cutting sheath remains in its position. After the locking, the cutting sheath protrudes beyond the tip of the biopsy cannula. Therefore, after the locking of the tension slide, the cutting sheath is rotated back to the starting position (opposite direction of rotation); the gear 74 will move in the proximal direction in the toothed roller. After releasing of the tension slide, the biopsy cannula/cutting sheath with gear slides back towards the distal direction with the biopsy cannula carrier. Now, the cutting sheath can again be moved in the proximal direction in order to open the sample removal chamber.

The proximal end of the cutting sheath is connected to the hollow biopsy cannula by a seal element 76, able to move in rotation, but air-tight, so that neither air can get in between biopsy cannula and the cutting sheath coaxially surrounding it, nor can air escape during excess pressure. On the proximal end of the biopsy cannula 2 is mounted air-tight a round, likewise hollow plastic part 47, being frictionally joined to the biopsy cannula. The plastic part 47 has a bearing element 49 at its distal end, which is press-fitted into the biopsy cannula carrier; at its proximal end, protruding from the hand piece 1, there is inserted another plastic part 112, which can turn relative to the plastic part 47 and the biopsy cannula 2. Between biopsy cannula and plastic part 112 there is inserted an O-ring seal. The plastic part has a plug 17 at its proximal end, onto which the connection element 4 is placed air-tight.

There is also a knurled disk 80 on the proximal end, protruding from the biopsy cannula carrier and the housing, by which, when rotated, the position of the sample removal chamber can be adjusted radially, without altering the position of the cutting sheath. One rotation of the biopsy cannula involves only one rotation of the sample removal chamber and, thus, the sample removal device. The plastic part 47 with biopsy cannula and cutting sheath is press-fitted into the biopsy cannula carrier with the bearing element 49 and the threaded spindle nut 75. The biopsy cannula can rotate in the biopsy cannula carrier and is mounted in the cutting sheath by the bearing element 49 and its narrow guide in the cutting sheath, and it can shift in the lengthwise axis with the biopsy cannula carrier. As described above, the cutting sheath is axially movable by rotation relative to the biopsy cannula. A polygon 50 (positioned proximal of the bearing element 49) is arranged on the plastic part, which can lock with the biopsy cannula carrier by tension, so that the sample removal chamber of the biopsy cannula can be brought into the most favorable position for the biopsy removal and held there by means of the knurled disk 80.

Details of the sample removal chamber and the tip of the biopsy cannula are represented in FIG. 5F. The sample removal chamber 71 adjoining the needle tip is open above for approximately 25% of its cross section. The cutting edges, including the distal circumference of the cutting sheath 3 and the sides of the sample removal chamber 72 on the biopsy cannula, may be grounded or sharpened. The sample removal chamber is between approximately 15 and 25 mm in length. It adjoins the cavity of the biopsy cannula. At the transition, i.e., the proximal end of the sample removal chamber, the cross section of the cavity of the biopsy cannula is closed between approximately 50% and 75% by a narrowing, e.g., a stopper 79. The height of the stopper is chosen such that it extends downward past the recess of the sample removal chamber. In this way, the vacuum will especially draw in the tissue sample through the continuous opening of the sample removal chamber and bring the tissue sample up against the wall of the sample removal chamber.

When there is excess pressure in the cavity of the biopsy cannula, the narrowing or stopper has a pressure boosting effect. The stopper has roughly the length of 10 mm and is glued or welded into the cavity. When using laser welding, it has proven to be advantageous to make the distal side of the stopper thin for a short length, around 2 mm, by removing material at the end surface. As a result, in this region at the end surface the tube of the biopsy cannula is welded to the end surface of the stopper and is air-tight at the end surface. The stopper can also be of shorter length, as long as the same effect is achieved. Thus, the stopper can also be replaced by a lip or a partial plug of approximately the same height. The important thing is that the narrowing is configured such that the vacuum is brought to bear primarily from the bottom in the sample removal chamber, so that the sample clings to the wall of the sample removal chamber during the cutting process and does not change in length. It has also proven to be advantageous to provide additional fixation means on the sample removal wall.

The suctioning of the sample from the bottom into the sample removal chamber produces, first, a high fill ratio of the sample removal chamber and, second, especially due to its configuration, a good fixation of the sample on the wall. Since the cutting sheath separates the sample at the outside of the biopsy cannula, this firm suctioning of the sample into the interior is also preserved during the separation process. Furthermore, due to the cutting sheath arranged on the outside, and the vacuum applied, no tissue is suctioned into the hollow cutting sheath and thus the tissue cannot get twisted or turned by the rotating lengthwise movement of the cutting sheath, as it is held fast in the interior of the cutting sheath. This improves the quality of the sample, since the pathologist obtains original material corresponding to the cross section of the cut and not being twisted or deformed. When the sample is ejected under pressure, a complete cleaning of the sample removal chamber occurs in addition through the stopper 79, so that no commingling occurs when used repeatedly. Since the vacuum generating device is used at the same time as a pressure generating device, the entire cavity is cleaned, especially that of the cannula.

FIG. 5H shows the drive and the installation of the vacuum pressure generating device 5 (view from the rear, i.e., opposite the Z-axis, housing cover and lower housing piece left out). In the upper-right proximal region, the vacuum pressure generating device 5 is arranged as a piston/cylinder unit 69. It consists of a syringe body 52 with threaded spindle 53 arranged inside, at whose end facing the syringe bottom there is fastened a plunger with seal elements—as is commonly known with syringes. At the end of the syringe body 52 facing the base block 8, a threaded spindle nut is arranged on the threaded spindle with a gear 55 formed at the circumference. The threaded spindle nut has one or more thread turns. The threaded spindle 53 interacts with the threaded spindle nut. The spindle has a pitch of around 5 mm per turn, so that at each rotation the plunger is moved out from the syringe body by a precisely defined amount, i.e., away from the syringe bottom, or toward the syringe bottom, depending on the direction of turning.

The toothed crown 55 arranged on the circumference of the threaded spindle nut meshes with the drive pinion 56, which is fastened on the take-off shaft of the DC gear motor 58. The take-off shaft of the DC gear motor 58 is mounted in the base block 8; for this, the take-off shaft is inserted into the transverse plate 59 of the base block. When the DC gear motor 58 is activated, the plunger is moved toward the syringe bottom or in the direction of the base block 8, depending on the direction of turning. The drive motor used is likewise a DC motor with high speed, connected to a planet transmission with high reduction ratio. It corresponds to the motor already described for the cocking mechanism.

The plunger is configured in familiar fashion as a syringe plunger. The syringe body made from plastic, being a cylinder with a bottom, is transparent. In order to prevent a twisting of the threaded spindle 53 upon actuation of the threaded spindle nut, the two opposite surfaces of the threaded spindle are plane in configuration. The threaded spindle is inserted into the insert element by its free end. The spacing between the surfaces of the threaded spindle corresponds to the width of the U-shaped insert element of the base block 8. There is only slight play between the U-shaped cross section of the insert element and the spindle surfaces at either end. The threaded spindle nut thrusts against the base block. In order to prevent the syringe body from sliding out upon turning of the threaded spindle nut, the bearing surface at the base block 8 is slightly conical toward the bottom. The connection piece of the syringe body is inserted into the passage 16 of the proximal end cover 7 so that the syringe body is held in roughly horizontal position. In addition, a pin pressed into the machined aluminum motor block may also be provided to prevent the syringe from rotating. The pin rests against the plastic syringe body when the needle is loaded into the housing properly. When the lid is closed the pin digs into the syringe slightly and prevents the syringe from rotating.

If the syringe plunger is moved beyond the ventilation opening 67 (FIG. 5H)—when the vacuum is no longer required—intake of air (atmospheric pressure) through the ventilation opening 67 will dissipate the previously established vacuum in the hollow biopsy cannula. If, then, the direction of turning of the gear motor is reversed, the vacuum pressure generating device will build up an excess pressure in the system by retraction of the plunger (toward the bottom of the syringe), which brings about the ejection of the tissue sample after opening the sample removal chamber. Moreover, the pressurized air will clean not only the sample removal chamber, but also in particular the inside of the biopsy cannula. The stopper narrowing the cavity of the cannula will make it difficult or entirely prevent tissue parts from getting into the cavity of the biopsy cannula. The narrowing of the cannula cavity by the stopper 79 will increase the pressure at the sample removal chamber and thereby improve the ejection of the sample, even when the sample removal chamber is half open.

This invention has been described and specific examples of the invention have been portrayed. While the invention has been described in terms of particular variations and illustrative figures, those of ordinary skill in the art will recognize that the invention is not limited to the variations or figures described. In addition, where methods and steps described above indicate certain events occurring in certain order, those of ordinary skill in the art will recognize that the ordering of certain steps may be modified and that such modifications are in accordance with the variations of the invention. Additionally, certain of the steps may be performed concurrently in a parallel process when possible, as well as performed sequentially as described above. Therefore, to the extent there are variations of the invention, which are within the spirit of the disclosure or equivalent to the inventions found in the claims, it is the intent that this patent will cover those variations as well. Finally, all publications and patent applications cited in this specification are herein incorporated by reference in their entirety as if each individual publication or patent application were specifically and individually put forth herein. 

1. A method for performing a biopsy comprising: providing a cannula having a lumen, a closed distal end and an orifice located on a circumferential surface of said cannula, wherein a sheath is slidably or rotatably disposed on said cannula; generating a negative pressure, relative to an atmospheric pressure, in the lumen of said cannula; inserting said cannula into a body of tissue within a patient while said orifice is covered by said sheath; exposing said orifice to capture a sample of said body of tissue in the lumen of said cannula; displacing said sheath to cover said orifice with said sheath thereby separating said sample from said body of tissue; removing said cannula from said patient's body; generating a positive pressure, relative to said atmospheric pressure, in the lumen of said cannula while the orifice of said cannula is covered with said sheath; and after generating said positive pressure, sliding said sheath to at least partially uncover said orifice to expose said sample of said body of tissue.
 2. The method according to claim 1, further comprising ejecting said sample of said body of tissue from said cannula.
 3. The method according to claim 2, wherein a stopper is positioned in said lumen of said cannula in a location proximal to said orifice, said stopper being adapted to partially obstruct said lumen and prevent said sample of said body of tissue from migrating to a proximal end of said cannula.
 4. The method according to claim 3, wherein said cannula further comprises a pressure generating device connected to a proximal portion thereof.
 5. The method according to claim 4, wherein said cannula further comprises a valve positioned between said cannula and said pressure generating device.
 6. The method according to claim 4, wherein a seal is provided between said cannula and said sheath.
 7. The method according to claim 4, wherein said pressure generating device comprises a chamber, said chamber comprising a piston slidably disposed therein, whereby when said piston is displaced in a proximal direction, said negative pressure is generated in said chamber, said chamber further comprising a proximal air inlet, and a distal port in communication with said cannula, wherein when said piston is displaced past said air inlet in a proximal direction, air enters said chamber to normalize pressure in said cannula, and wherein when said piston is displaced past said air inlet in a distal direction, said positive pressure is generated in said chamber.
 8. The method according to claim 1, further comprising detecting said positive pressure with a sensor.
 9. The method according to claim 3, wherein the step of exposing said orifice to capture a sample of said body of tissue further comprises the step of sliding said sheath in a proximal direction of said cannula and exposing a distal portion of said orifice first before completely exposing said orifice.
 10. The method according to claim 3, wherein the step of sliding said sheath to expose said sample of said body of tissue comprises sliding said sheath in a proximal direction of said cannula and exposing a distal portion of said orifice.
 11. The method according to claim 3, wherein said sheath is coaxially placed over said cannula.
 12. A method for extracting a tissue sample from a patient's body comprising the acts of: inserting a chamber into the patient's body, wherein said chamber comprises an opening with a sheath slidably disposed over said opening to cover said opening; generating a low pressure environment in said chamber relative to a pressure surrounding said chamber; displacing said sheath to uncover said opening and capturing said tissue sample through a suction resulting from said low pressure environment; covering said opening with said sheath and in the process severing the captured said tissue sample; removing said chamber from said patient's body; after the act of removing, generating a high pressure environment in said chamber relative to an atmospheric pressure surrounding said chamber while said chamber containing the captured said tissue sample is covered with said sheath; and displacing said sheath to open said chamber to eject the captured said tissue sample.
 13. The method according to claim 12, wherein said chamber comprises a proximal end and a distal end, and wherein a channel, having an opening at the proximal end of said chamber, is adapted to connect said chamber to a pressure generating source.
 14. The method according to claim 13, wherein the step of uncovering said opening and capturing said tissue sample further comprises exposing a distal portion of said opening prior to completely exposing said opening.
 15. The method according to claim 13, wherein the step of opening said chamber to eject said tissue sample comprises opening a distal portion of said opening.
 16. The method according to claim 13, wherein said pressure generating source comprises a single acting cylinder with a piston slidably positioned within said cylinder for displacing a volume of fluid, a port positioned at the distal end of said cylinder is connected to said channel, and an orifice at the proximal portion of said chamber is configured to allow air inflow into the cylinder when said piston is displaced in a proximal direction and past said orifice.
 17. A method for performing a biopsy comprising the ordered acts of, without precluding one or more additional intervening acts: providing a cannula having a closed distal end and an orifice located on a circumferential surface of said cannula, wherein a sheath is slidably or rotatably disposed on said cannula; generating a negative pressure, relative to an atmospheric pressure, in a lumen of said cannula; inserting said cannula into a body of tissue within a patient while said orifice is covered by said sheath; exposing said orifice to capture a sample of said body of tissue in the lumen of said cannula; covering said orifice with said sheath and in the process separating said sample from said body of tissue; removing said cannula from said body of tissue; generating a positive pressure relative to the atmospheric pressure in a channel in fluid communication with the lumen, while the orifice of said cannula is covered with said sheath; and sliding said sheath to expose said sample tissue and expelling the sample by flowing air resulting from the positive pressure by either permitting the air under positive pressure to enter the lumen before sliding the sheath or permitting the air under positive pressure to enter the lumen after sliding the sheath.
 18. The method according to claim 17, wherein a stopper is positioned in said lumen of said cannula in a location proximal to said orifice, said stopper being adapted to partially obstruct said lumen and prevent said sample of tissue from migrating to a proximal end of said cannula.
 19. The method according to claim 18, wherein said cannula further comprises a pressure generating device connected to a proximal portion thereof.
 20. The method according to claim 19, wherein the expelling includes flowing air resulting from the positive pressure by permitting the air under positive pressure to enter the lumen after sliding the sheath by opening a valve positioned between said cannula and said pressure generating device.
 21. The method according to claim 20, wherein a seal is provided between said cannula and said sheath.
 22. The method according to claim 20, wherein said pressure generating device comprises a chamber, said chamber comprising a piston slidably disposed therein, whereby when said piston is displaced in a proximal direction, said negative pressure is generated in said chamber, said chamber further comprising a proximal air inlet, and a distal port in communication with said cannula, wherein when said piston is displaced past said air inlet in a proximal direction, air enters said chamber to normalize pressure in said cannula, and wherein when said piston is displaced past said air inlet in a distal direction, said positive pressure is generated in said chamber.
 23. A method for performing a biopsy with a biopsy device that includes a cannula having a lumen, a closed distal end, and an orifice located on a circumferential surface of said cannula, and wherein a sheath is disposed on said cannula to selectively cover and uncover said orifice, comprising: suctioning tissue through said orifice and into said lumen of said cannula while said cannula is positioned in a body of a patient; displacing said sheath to cover said orifice with said sheath and in the process of displacing said sheath separating a tissue sample from said tissue; after displacing said sheath, removing said cannula containing said tissue sample from said body of said patient; after said cannula containing said tissue sample is removed from said body of said patient, generating a positive pressure, relative to said atmospheric pressure, in said lumen of said cannula while said orifice of said cannula is covered with said sheath; and after generating said positive pressure, sliding said sheath to at least partially uncover said orifice to eject said tissue sample as a result of said positive pressure. 